Cleanup: use base::StringPrintf instead of snprintf in WebTestProxy.

BUG=none

Review URL: https://codereview.chromium.org/408163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284810 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed